Wheel device for skate board or rolller skate

ABSTRACT

Disclosed is a wheel device for a skate board or a roller skate. A wheel includes a single central hub having an exterior wall and a bore for the housing of rollers, the rollers providing the connection with the hub of a truck; and a tread removably mounted on the exterior wall of the hub. A shoulder of the tread includes a first support face and a second support face, the two faces being parallel to each other and perpendicular to the common axis. The tread is locked in rotation and in axial position on the hub by means of locking screws, including heads abut against the second support face of the shoulder, the screws traversing the shoulder from side to side and attaching on the connecting means of the hub.

FIELD OF INVENTION

The invention relates to a wheel device for skate board or roller skate.

It relates to the technical field of systems of holding a tread (or tire) in position on a wheel hub.

PRIOR ART

Wheel devices for skate board or roller skate comprising a wheel mounted on truck are known, the aforementioned wheel comprising a central hub having a single bore for the housing of rollers, the aforementioned rollers providing the connection of the aforementioned hub with the aforementioned truck. A removable tread is mounted on the exterior wall of the hub, connecting means enabling holding in position of the aforementioned tread on the aforementioned hub.

This type of mounting is particularly advantageous because it enables easy changing of the tread when it is worn or when the user wishes to modify the characteristics (tread made of rigid, flexible material, including an air chamber, . . . ), without having to dismount the hub or the rollers.

Such devices are described for example in the following patent documents:

-   -   FR 2,369,855 (MATTEL) wherein the hub comprises a series of         radial ribs designed to be lodged in complementary grooves         provided in the tread for a radial locking. The maintenance         axial position of the tread on the hub is achieved by means of a         cap configured to be screwed into the aforementioned hub by         bearing on the aforementioned tire;     -   FR 930,820 (MARCHAND) wherein a tread is mounted on the hub. The         holding in position of the tread on the hub is carried out by         elastic blades terminated by hooks;     -   CH 595,860 (PERUHAG) wherein the hub comprises an annular bulge         designed to be housed in an annular groove formed on the tread.         This connection provides a axial and radial locking of the tire         relative to the hub;     -   U.S. Pat. No. 2,635,923 (ISHAM) wherein the hub has an external         thread designed to be screwed into an internal thread provided         on the tread. The holding in position of the tire on the hub is         carried out by means of a cap configured to be screwed into the         hub by bearing on the aforementioned tire;     -   U.S. Pat. No. 2,627,440 (KLEIN) wherein a tread is mounted         around the hub. The connection between the hub and the tread is         acheived by means of a shell inserted in the interior the         aforementioned tread and wherein the aforementioned hub is         screwed. The radial locking of the tread on the shell is         provided by a screwed cap;     -   U.S. Pat. No. 2,304,944 (MARTINEC) wherein a nut is screwed into         the hub. The nut and the hub are provided with lips penetrating         into complementary grooves formed in the tread. These lips,         combined with the tightening of the nut, enable radial and axial         locking of the tire;     -   GB 06752 (HERBERT) wherein the tread is locked in rotation on         the hub by means of a projecting rib that engages in a         complementary groove provided in the shoulder of the         aforementioned tread. The axial locking is provided by a cover.     -   FR 2,875,143 (LENOIR), U.S. Pat. No. 2,038,453 (SMITH), U.S.         Pat. No. 1,100,242 (COBB) or U.S. Pat. No. 2,136,531 (VOGT)         wherein a pair of flanges act to radially and axially lock the         tread on the hub.

All these solutions known from the prior art have a number of disadvantages. Indeed, at medium speeds (for example greater than or equal to 3500 rev/min for a wheel diameter of 70 mm) or high (for example greater than or equal to 7500 rev/min for a wheel diameter of 70 mm), these connections generate vibrations that make the practice of skate boarding or roller skates cumbersome, even difficult. Furthermore, it was found that the hub/tread connection caused overheating detrimental to holding in position of the aforementioned tread. Risks of loosening of the tread were also found. This is due to the fact that, at medium or high rotation speeds, the tread is stretched by centrifugation and alters the connection with the hub (or the locking flanges). This loosening phenomenon is amplified by using a soft tread.

The main objective of the invention is to remedy this state of affaires. In particular, an object of the invention is to limit the vibrations at medium or high speeds. Another object of the invention is to limit the temperature rise at the hub/tread connection. Yet another object of the invention is to eliminate the risk of loosening of the tread.

DISCLOSURE OF THE INVENTION

The solution offered by the invention is a wheel device for skate board or roller skates, comprising a wheel mounted on a truck, the aforementioned wheel comprising:

-   -   a single central hub single having a bore for the housing of         rollers, the aforementioned rollers providing the connection         with the aforementioned hub of the aforementioned truck,     -   a tread removably mounted on the exterior periphery of the hub.

The device is remarkable in that the tread has a bore provided with a shoulder forming housing for the hub, the interior wall of the aforementioned shoulder radially positioning the exterior wall of the aforementioned hub, the aforementioned tread being locked in rotation and in axial position on the aforementioned hub by means of a locking screw traversing the aforementioned shoulder from side to side and attaching on the connecting means of the aforementioned hub.

By traversing the tread from side to side, the screws provide a complete rotational and axial locking of the aforementioned tread on the hub. All relative movement of the tread and of the hub being eliminated, the risks of heating are zero. In addition, at medium or high rotation speeds, the periphery of the tread is stretched by centrifugation, but does not alter in anyway its connection with the hub, the locking of the aforementioned tread being fully ensured. The device object of the invention thus enables a particularly fine and very safe practice of roller devices, whatever the rotational speeds.

Other features of the invention are listed below, each of these features can be considered alone or in combination with the remarkable features defined above:

-   -   the hub comprises radial attachment brackets each comprising at         least an axial bore for the passage of locking screws; axial         bores for the passage of locking screws traverse the shoulder of         the tread from side to side, the aforementioned bores being         arranged so as to be positioned opposing bores of the attachment         brackets when the aforementioned tread is mounted on the hub;         the locking screws traverse the bores of the attachment brackets         and of the shoulder.     -   the blocking screws are positioned at equal distance from each         other.     -   the attachment brackets are connected to each other, the         connection between the aforementioned brackets comprising axial         orifices for air circulation.     -   the tread comprises axial orifices for air circulation.     -   the attachment brackets comprise a front face positioned against         the tread and a rear face opposed to the aforementioned front         face, the aforementioned rear face being provided with ribs         positioned on both sides of the axial bore.     -   the ribs are spaced so that a clamping nut of the locking screw         can be housed between the aforementioned ribs.     -   the axial bore of the attachment brackets is tapped, the         aforementioned tapping extending on the interior flanks of the         ribs.     -   the tapping formed on the interior flanks of the ribs is not         coaxial with the tapping in the attachment brackets, so that the         aforementioned ribs exert a clamping force on the locking         screws.     -   the tread comprises ribs stiffening the periphery of the         aforementioned tread, the aforementioned ribs being arranged         between one of the support faces of the shoulder and the         internal bore of the aforementioned tread, the aforementioned         ribs being located at equal distance from each other and         positioned between the axial bores of the aforementioned tread.     -   protective washers are positioned on the truck, the         aforementioned washers being housed in the interior of the bore         of the hub, on both sides of the rollers, the aforementioned         washers comprising a circular lip whose exterior diameter         substantially corresponds to the interior diameter of the         aforementioned bore.

DESCRIPTION OF THE FIGURES

Other advantages and features of the invention will become apparent by reading the description of a preferred embodiment which follows, with reference to the accompanying drawings, made as examples and are not limiting and in which:

FIG. 1 is a schematic bottom view of a skateboard or skateboard,

FIG. 2 is an enlarged view of section A-A of FIG. 1, this figure showing a device in accordance with the invention,

FIG. 3 is a radial sectional view of a hub in accordance with the invention,

FIG. 4 a is a radial sectional view of a tread in accordance with the invention,

FIG. 4 b is a radial sectional view of a tread in accordance with the invention, in an implementation variant,

FIG. 5 is an enlarged view of section A-A of FIG. 1, showing the device in accordance with the invention in an implementation variant,

FIG. 6 is a radial sectional view of a hub in accordance with the invention, in an implementation variant.

IMPLEMENTATION MODES OF THE INVENTION

The invention applies particularly to skateboards (ie skateboards in English), to roller skates, commonly called “quad,” or to any other similar wheeled device.

Referring to FIG. 1, a skateboard generally comprises a deck 10 on which are attached trucks 11 (referred to as “trucks” in English). These trucks 11 are positioned at the front and rear of the deck 10. Wheels 12 are mounted cantilevered at each of the ends of the trucks 11. Each truck 11 is thus equipped with a pair of wheels 12. For roller skates, examples of cantilevered mounting of wheels are described in the document FR 930,820 (MERCHANT), to which the person of skill in the art can refer.

In FIG. 2, the device object of the invention comprises a single central hub 20 having a generally substantially cylindrical shape. The hub 20 is made of a material such as steel, aluminum or rigid thermoplastic, optionally fiber-filled. It is obtained by machining, molding, stamping, or any other similar processes.

The hub 20 has an internal bore 23 (FIG. 3) for the housing of rollers 21. This axial bore 23 traverses the hub 20 from side to side. In practice, each wheel 12 is provided with a pair of rollers having single row of balls with radial contact, double sealed, optional bushing joints, lubricated for life and maintenance free. A mounting with a single roller having double row of balls or having rollers can however be considered. The internal diameter of the bore 23 is dimensioned to tightly receive the exterior rings of rollers 21. A circular shoulder 22, positioned in the middle of the bore 23, enables axial stopping of the exterior rings of the rollers 21 and centering of the latter. The interior rings of rollers 21 are mounted sliding true on the truck 11, the aforementioned rollers thus assuring a pivot connection between the hub 20 and the aforementioned truck.

The exterior wall 220 of the hub 20 is concentric with the internal bore 23 and comprises attachment brackets 24, which extend away from the aforementioned wall. In FIG. 3, the number of attachment brackets 24 is equal to three, but a greater or lesser number (preferably at least two) can be considered. These brackets 24 are of identical shapes and are arranged in star, equidistant from each other to ensure a good balance (three legs arranged at 120° in FIG. 3). On the implementation example of FIGS. 2 and 5, the brackets 24 are off center on the exterior wall of the hub 20, being closer to one of the edges of the aforementioned hub. In practice, the exterior wall of the hub does not have any obstacles between the brackets 24 and the other edge.

Referring to FIG. 2, the attachment brackets 24 each comprise a front face 240 designed to be positioned against a shoulder 32 of the tread 3 and a rear face 241 opposite to the aforementioned front face. In practice, the two front and rear faces 240 and 241 are parallel to each other and perpendicular to the common axis A of the hub 20, of the internal bore 23 and of the tread 3. Preferably, the brackets 24 are integral with the hub 20 by being shaped during the manufacturing process of the latter. It is however envisionable to bring the brackets 24 on the exterior wall of the hub 20, fixing them for example by welding or by a mechanical linkage. One can provide in this case to make the attachment brackets 24 in a material other than that constituting the hub 20. Advantageously, the brackets 24 are separated from each other (FIG. 3) so that air can possibly move between them. In an implementation variant not shown, the attachment brackets 24 are connected to each other, the connection between the aforementioned brackets can have axial orifices for the circulation of air.

Referring to FIGS. 2 and 3, the mounting attachment brackets 24 each comprise at least an axial bore 25 for the passage of locking screw 4. Preferably each bore 25 opens on the two faces 240 and 241 of the attachment brackets 24. These bores 25 are arranged on a common concentric diameter with the internal bore 23, are positioned at equal distance from each other and are parallel to the common axis A. The rear face 241 of the brackets 24 is provided with ribs 26 positioned on either side of the axial bores 25, equidistant from the latter. In other words, each bore 25 opens advantageously in the middle of a groove (delimited by the two ribs 26) made on the rear face 241. The ribs 26 are configured to axially stiffen the attachment brackets 24.

Referring to FIGS. 2 and 4, the tread 3 (or tire) is removably mounted on the exterior wall of the hub 20. The tread 3 has a substantially cylindrical general shape. Preferably, the tread 3 is made entirely of rigid polyurethane obtained by molding. In the case where the tread 3 is made in part of soft polyurethane, the latter being capable of stretching under the effect of the centrifugal force, the aforementioned tread is advantageously made of bi-material: soft polyurethane on the periphery cast molded or bonded onto a rigid thermoplastic or aluminum type core. The thread 3 can also be made of rubber with an interior air chamber tube mounted on an aluminum or thermoplastic rim.

The tread 3 can have an internal bore 33 (FIGS. 4 a, 4 b) axially traversing the aforementioned tread from side to side and whose diameter is larger than the exterior diameter of the attachment brackets 24 of the hub 20. A circular shoulder 32, positioned substantially in the middle of the bore 33, enables reception of the hub 20. The shoulder 32 can be off centered, however. In practice, the interior diameter of the shoulder 32 is concentric with the exterior periphery of the tread 3 and substantially corresponds to the exterior diameter of the hub 20, so that the hub 20 is centered and therefore radially maintained in the shoulder 32. In other words, the interior wall 320 of the shoulder 32 radially positions the exterior wall 220 of the hub 20. Referring to FIG. 4 a, the interior wall 320 of the shoulder 32 is cylindrical. In an implementation variant shown in FIG. 4 b, the interior wall 320 can be partially cylindrical, thus forming a reduced span for centering on the hub 20. The shoulder 32 comprises a first support face 330 and a second support face 331, both of the aforementioned faces being parallel to each other and perpendicular to the common axis A. The tread 3 is put in place on the hub 20 so that the first support face 330 acts to abut against the front face 240 of the attachment brackets 24. The tread 3 is thus axially positioned and centered on the aforementioned hub. As described in the following paragraph, it is essentially the locking screw 4 that provides the maintenance in axial position and prevents the rotation of tread 3 on the hub 20.

Referring to FIG. 4 a, multiple axial orifices 36 traverse the shoulder 32, from the first support face 330 to the second support face 331. These orifices 36 are distributed between the attachment points of the tread 3 to allow air circulation. They correspond to the empty spaces left between the fixing attachment brackets 24 and enable, by circulation of air, limitation of heatings due to high rotation speeds of the wheel. In FIG. 4 b, the orifices 36 extend and open into the interior diameter of the shoulder 32. In any event, for treads 3 that are not subjected to high speeds, the orifices 36 are not mandatory.

The tread 3 comprises axial bores 35 for the passage of screws 4. These bores 35 are arranged on a common diameter concentric with the interior diameter of the shoulder 32, are positioned at equal distance from each other and are parallel to the common axis A. They traverse the shoulder 32 from side to side, (that is to say, they open up on support faces 330 and 331) and are arranged to be positioned vis-a-vis the bores 25 of the attachment brackets 24 when the tread 3 is mounted on the hub 20. In this position, the locking screws 4 (or any other similar fastening means) can be inserted into the bores 35, 25 so as to traverse the shoulder 32 from side to side and re-emerge at the attachment brackets 24 in order to lock the tread 3 in axially position and in rotation on the hub 20. Such a mounting enables compensation for all the dimensional plays between tread 3 and the hub 20. In practice, the central part of the tread 3 comprising the shoulder 32 is designed so as not to creep while withstanding the stress of the pressure of the locking screws 4 and the stress of the effects of centrifugation due to the high operational rotation speeds. In particular, the width, thickness and material used to make the shoulder 32 will be selected by person of skill in the art so that the aforementioned shoulder is sufficiently rigid in order to not be subjected to creep under the compressive stress of screw 4 and under stress from medium or high centrifugal rotation speeds. One will note that the locking screws 4 are positioned at equal distance from each other, thus avoiding any imbalance on the wheel. To stiffen the periphery of the tread, the latter can include ribs (not shown) arranged between one of the support faces 330 and/or 331 of the shoulder 32 and the interior wall 320 of the aforementioned shoulder the internal bore 33. These ribs will be located at equal distance from each other and positioned between the axial bores 35 of the tread 3, so as to obstruct neither the positioning of the screw heads 40, nor the installment of the aforementioned tread against the attachment brackets 24 of hub 20.

In the mounting of FIG. 2, the screw heads 40 come into abutment against the first second support face 330 331 of the shoulder 32. The other end of screws 4 re-emerge between the ribs 26 made on the rear face 241 of the attachment brackets 24 and are screwed into into a locking nut 41. The ribs 26 are spaced so that the nut 41 can be lodged between the aforementioned ribs. In practice, locking nuts are used. It is not necessary to use a wrench to hold the nuts 41 during screwing, because the ribs 26 are configured to block the rotation of the aforementioned nuts. In this attachment mode, bores 25, 35 are smooth.

In an implementation variant shown in FIGS. 5 and 6, the screws 4 are screwed directly into the attachment brackets 24, without it being necessary to use locking nuts. In this case, the axial bore 25 of the attachment brackets 24 is threaded. The ribs 26 are closer together than in the previous implementation mode so that the tapping extends on the interior flanks the aforementioned ribs. A permanent deformation is subsequently formed out on the exterior of the ribs 6 (with a press for example) so that they can approach each other. The tappings 25 of the brackets 24 are then no longer coaxial with tappings of the ribs 26. And the screws, by introducing, act to pin up the ribs of 26 at their initial position. In this way, the ribs 26 can exert a clamping (thus braking) force on the screws 4, preventing the latter from unscrewing. For thus implementation mode, the hub 20 is preferentially made of steel.

Referring to FIG. 2 and to FIG. 5, the protection washers 5 are positioned on the truck 11, and are lodged in the interior of the bore 23 of the hub 20, on both sides of the rollers 21. These washers 5 comprise a circular lip 51 whose exterior diameter substantially corresponds (with a sufficient functional play) to the interior diameter of the bore 23. Once pressed against a rollers 21, the axial end of the lip 51 is close (with a sufficient functional play) to the face of the exterior ring of the aforementioned rollers, the latter thus being completely protected. The washers 5 can be made from steel, aluminum, or rigid thermoplastic. They can also be bi-material, their central part being made of steel and their circular lip made of molded elastomer. Thus, the axial end of the lips 51 can act to lightly run against the exterior rings of the rollers 21.

In practice, the mounting of the wheel 12 in the truck 11 is carried out in the following manner: the rollers 21 are positioned on the bore 23 of the aforementioned hub. A first washer 5 is inserted on the truck 11 so as to come to abut against a shoulder 110 of the aforementioned truck. The hub-roller mounting is inserted on the truck 11 so as to act to abut against the previously installed washer 5. The mounting is on the truck 11 so that the side of the hub 20 bearing the attachment brackets 24 is first inserted for the aforementioned truck. In this way, the attachment brackets 24 are not an obstacle to the subsequent demounting of the tread 3. The second washer 5 is inserted on the truck 11 so as to act to abut against the interior ring of the rollers 21. A locking nut is screwed on the threaded end of the truck 11 so as to act to axially arrest the mounting assembly. The nut 112 has an outside diameter less than the interior diameter of the shoulder 32 of the tread 3 so as not to obstruct the dismounting of the latter. The tread 3 is then attached on the hub 20. To change the thread 3, it is not necessary to dismount the mounting assembly. It suffices to remove the locking screw 4 and axially pull on the aforementioned tread so as to slide out of the hub 20. The locking nut 112 is thus no longer stressed during the changing of the tread 3. Its locking power will thus retain all of its operational effectiveness.

In summary, and in a nonlimiting manner, the device of the invention provides a hub having integrated rollers whose configuration enables full use of the capacity of the aforementioned rollers and avoidance of occurrence of heating problems. It also enables avoidance of entry of dust into the hub having integrated rollers. In addition, the user can mount, on a single roller having single integrated bearings, multiple types of tires having different characteristics: tire made of rigid material, tire made of flexible material, tire including an air chamber, etc. A simple and effective connection is provided between the hub having rollers and the tread, this connection integrating a compensation for all the dimensional plays between the aforementioned hub and the aforementioned thread. Any risk of loosening of the tread in operation is eliminated. The rising temperature of the tread rubbing on the ground is limited by promoting the flow of air in the mounting. 

1. A wheel device for skate board or roller skate comprising a wheel mounted on a truck, the aforementioned wheel comprising: a single central hub having an exterior wall and a bore for the housing of rollers, the aforementioned rollers providing the connection with the aforementioned hub of the aforementioned truck, a tread removably mounted on the exterior wall of the aforementioned hub, the aforementioned hub, the aforementioned interior bore and the aforementioned tread having a common axis, characterized by the fact that: the tread has a bore provided with a shoulder forming a housing for the hub, the aforementioned shoulder comprising an interior wall radially positioning the exterior wall of the aforementioned hub, the aforementioned shoulder comprising a first support face and a second support face, the aforementioned two faces being parallel to each other and perpendicular to the aforementioned common axis, the aforementioned tread being locked in rotation and in axial position on the aforementioned hub by means of locking screws, which screws comprise heads which abut against the second support face of the shoulder, the aforementioned screws traversing the aforementioned shoulder from side to side and attaching on the connecting means of the aforementioned hub.
 2. A device according to claim 1, wherein: the hub comprises radial attachment brackets each comprising an axial bore for the passage of locking screws, axial bores for the passage of locking screws traverse the shoulder from side to side through of the tread, the aforementioned bores being arranged so as to be positioned opposing bores of the attachment brackets when the aforementioned tread is mounted on the hub, the locking screws traverse the bores of the attachment brackets and of the shoulder.
 3. A device according to claim 2, wherein the attachment brackets are connected to each other, the connection between the aforementioned brackets comprising axial orifices for air circulation.
 4. A device according to claim 1, wherein the tread comprises axial orifices for air circulation.
 5. A device according to claim 2, wherein the attachment brackets comprise a front face positioned against a support face of the tread and a rear face opposed to the aforementioned front face, the aforementioned rear face being provided with ribs arranged on both sides of the axial bore.
 6. A device according to claim 5, wherein the ribs are spaced so that a clamping nut of the locking screw can be housed between the aforementioned ribs.
 7. A device according to claim 5, wherein the axial bore of the attachment brackets is tapped, the aforementioned tapping extending on the interior flanks of the ribs.
 8. A device according to claim 7, wherein the tapping formed on the interior flanks of the ribs is not coaxial with the tapping in the attachment brackets, so that the aforementioned ribs exert a clamping force on the locking screw.
 9. A device according to claim 2, wherein the tread comprises ribs stiffening the periphery of the aforementioned tread, the aforementioned ribs being arranged between one of the support faces of the shoulder and the internal bore of the aforementioned tread, the aforementioned ribs being located at equal distance from each other and positioned between the axial bores of the aforementioned tread.
 10. A device according to claim 1, wherein protective washers are positioned on the truck, the aforementioned washers being housed in the interior of the bore of the hub, both sides of the rollers, the aforementioned washers comprising a circular lip whose exterior diameter substantially corresponds to the interior diameter of the aforementioned bore. 